Conventionally, as bright pigments, scaly aluminum particles, graphite chip particles, scaly glass particles, scaly glass particles covered with silver, natural mica chip particles covered with a metal oxide such as titanium dioxide or iron oxide, and the like are known.
These bright pigments have the property of glittering by reflecting light from the surfaces thereof, and are used as materials for paint, ink, a resin composition for molding, and cosmetics. These bright pigments provide a coating surface obtained by applying paint, a printing surface using ink, or the surface of a resin molding molded using a resin composition for molding with a peculiar outer appearance having a wide variety and being excellent in beauty, in combination with the color tone of a base material of the surface.
Furthermore, as the bright pigments having a metallic luster, the following are known.
(1) Powder obtained by crushing aluminum powder or a foil-shaped resin covered with metal.
(2) Natural mica powder covered with metal.
These bright pigments have a metallic luster, so that they can provide an object to be used with a strong brightness appearance and provide the target to be used with an excellent outer appearance in terms of design.
Therefore, the bright pigment is mixed with paint used for coating of automobiles, motorcycles, OA equipment, mobile telephones, and household electric appliances, ink of various printed matters or writing instruments, or cosmetics and used for wide applications.
As examples of the bright pigments, for example, METASHINE (Registered Trademark) PS series already have been put on the market by the applicant of the present application. This bright pigment has a structure in which a scaly glass base is covered with silver.
When a coating is formed of paint containing a bright pigment whose base is covered with metal, there arise the following problems in some cases.
Corrosive substances such as a sulfur compound and a chlorine compound may be present in an environment in which the above coating is placed. In this case, metal is discolored with the passage of time, and the bright pigment loses an original metallic luster, resulting in that the coating loses an original outer appearance. The reason for this is considered to be as follows: the sulfur compound, the chlorine compound, or the like permeates the inside of the coating, and a part of the compound chemically reacts with metal covering the base, thereby corroding the metal.
In order to solve the problem, a bright pigment has been disclosed in which flake-shaped glass is covered with a metal coating layer and a dense protective coating layer in this order (for example, see Patent Document 1). The dense protective coating layer is made of a metal oxide. The dense protective coating layer is formed by dispersing flake-shaped glass covered with a metal coating layer in a predetermined alkaline solution for a predetermined period of time, and taking the flake-shaped glass covered with the metal coating layer out of the alkaline solution and sintering it. The predetermined alkaline solution contains metal alkoxide, water, and alcohol.
Furthermore, Patent Documents 2-4 disclose a paint composition for protecting a silver coating formed by vapor deposition. The paint composition described in Patent Document 2 contains a silicone acrylic resin and a zirconium complex of carboxylic acid as a silver inactivating component. The paint composition described in Patent Document 3 contains a silicone alkyd resin and a zirconium complex of carboxylic acid as a silver inactivating component. The paint composition described in Patent Document 4 is made of at least one resin selected from the group consisting of a silicone acrylic resin, a silicone alkyd resin, and a particular polyfunctional silicone cross-linking resin having a siloxane bond as a main chain.    Patent Document 1: JP 4-193725 A    Patent Document 2: JP 10-158572 A    Patent Document 3: JP 10-292152 A    Patent Document 4: WO 99/62646